Compensating let-off mechanism



March 14, 1933. H G R B NS N 1,90,952

COMPENSATING' LET-OFF MECHANISM Filed March 1, 1930 Patented Mar. 14, 1933 3 UNITED STATES,

.PATET ssice AMERICA, IN (1., A CORPORATION OF DELAWAR comrmvserme LET-OFF MECHANISM Application filed March 1,

This invention relates to appliances for controlling the delivery ofyarn, thread or. other articles of a similar character, such as wire and filaments, and is of particular utility when embodied. in the construction of a supply carrier for braiding machines, al though I contemplate the utilization of my improvements in any field for .which they are adapted by nature.

An important object of this invention is to apply a constant tension of uniform charactor to the yarn; thread or 'wire'as it is delivered from a supply carrier to a braiding machine or other mechanism in which the material is being used, the let-off arrangements being characterized by means for controlling them positively and with great sensitiveness, so that the supply may be fed quickly on .demand while a uniform tension is maintained.

A clear conception of the operation, construction and other features of the invention may be had from the following specifications and claims, in conjunction with the accompanying drawing, in which: i

Fig. 1 is a view in side elevation partially in section of a carrier adapted for use upon abraidingmachine, in which the features of this'invention are embodied.

Fig. 2 is a view at right angles to Fig. 1, certain parts being omitted for clearness of illustration.

Fig. 3 is a cross-section at 33 of Fig. 1.

F ig. 4 is a detailed vertical section of a part 'ofFig. 1, on a larger scale;

Fig. 5 is a schematic layout'ofthe machine in which the invention is used.

In the now preferred form of carrier, the base 1 is a circular plate as shown adaptedfor use in a braiding machine similar to that described in my co-pending application for Letters Patent, Serial No. 137 ,395 filed September 24,1926; 1 e V This base has a threaded bore/1, within which is screwed a post 5,' having a head 6 which serves to hold in place a plate 7, carrying the filling supply B andthe let-off mechanism is designated in general by L.

The filling supply B is shown as taking the form of a mass of yarn or thread Wound upon a conventional paper bobbin or tube 8 1930. Serial No. 432,338,

within'which extends a hollow shaft or cylin- 1 der 9, having an annular collar 2 fitted thereon; The use of this collar will be described hereinafter.

Within shaft 9 is a second hollow shaft 10,

separated from shaft 9. at the bottom. by a collar 11 and'atthe top by a similar collar- 12. Hollow shaft'10 is mounted on head 6 in such amanner that it hasa limited rota-' tive movement under constraint by a spring- 13, whichis fastened in headl6 at-thebottom and in a collar 14 at thetop, the collar.

14 actingas a spacing member between a dead'spindle 15 and the hollowshaft 10. Both shafts 9 and 10-areheld in 'ver'tical relation with spindle15 by means of a washer 16 and cotter pin 17. Forced on to the bot-.

tom of shaft 10 is a circular'plate20, on

which is mounted a post 19 carryinga part of the let-off mechanism. 1

Shaft 10 has a movement to and fro about spindle 15 under'control of spring 13 and shaft 9 is free to rotate with bobbin'S and the thread mass B about shaft 10 as an axis The operation of these parts will be ex-' plained hereinafter.

The let-ofi' mechanism illustrated comprisesan eye'18 formed in the top. of the post 19; from which extends upward a guide wire 21, having an eye 22 formed in its top.

Post 19 has an axially movable'c'ollar or rider 23 mounted thereon and normally pressed downward by a spring '24, this rider 23 having a guide eye 25 formed on one side. The plate 7 has two'splitarms 26,.formed thereon, in which is mounted a wire frame 27 shapedas shown in'Figs. 1 and 2 with a I guide eye 32 formed in its uppermost part. A cross bar of wire having an eye 28 in its center portion is spot-welded to frame 27 as shown, and asecond bar havingan eye 29 in its center portion is welded nearer the top of frame 27. A third cross bar 30 iswelded to the frame between the eyes 28 and 29, this bar supporting a socket 31 for holding a column 33, which extends upward from column 33.

I an arm formed on plate 7, as shown having i a socket or supportingmemberB for the.

The socket 31 constitutes the. upper jaw a piece of of a clamping device through which the yarn or thread is run, and has pegs 35, as shown in Fig. 2, which form a guide for the thread. Hinged to the upper jaw is a lower jaw 36, which is normally pressed against the upper jaw 31 by means of spring 37, the tension of which may be adjusted by collar 38 held to column 33 by set screw 39. Jaw 31 also forms a guide or hearing for a lever arm 40, which has a rocker-shaped part 41, and a hook 42 at its free upper end.

Attached to arm 40 by a hook 43 is a tension spring 44, which is fastened at its other end by hook 45. The operation of this spring will be explained hereinafter.

Passing through the upper jaw 31 is a pin 46, whichis in engagement with lower jaw 36, and is of suflicient length to be engaged and depressed by foot 41 when the arm 40 is raised against the tension of spring 44.

When arm 40. is in a position nearly vertical, the part 41 depresses pin 46 and forces jaws 36 away from jaw 31 compressing spring 37, thereby releasing the grip on the thread. 7

A detector member 47 may be provided for detecting broken threads, and is composed of wire having an eye 48 in its upper end, and which passes through an eye 49 in the collar 38, and thence through a bearing in'socket 34 which is cut away at 50 to form an open space in which a wire 51 may move. Wire 51 isspot-welded to member 47 and to apin 52, which is free to move up and down in a bearing in plug 5. This pin may be used to trip a lever, thereby stopping the braiding machine when'thethread breaks or to make an electrical contact for giving'an alarm, for example as described and claimed in my copendingapplication Serial No. 117,904, filed June 23, 1926.

Thecircular plate .2, already mentioned,

has on its periphery a series of ratchet teeth, such as those illustrated at 54, adapted to be engaged serially by a projection 3 on the rider 23 already described.

Plate 2 revolves with the bobbin B. The

thread 55 is taken off the bobbin B through eye 18 and then is drawn down and through eye 25, and passes thence through eyes 22 and 28 to the jaws 35 and 36 of the gripping device. The thread is then carried through eye 48 of detector bar 47, thence through eye 29 to the hook 42 on arm 40, and thence through eye 32 to the braiding point.

As the thread is pulled taut the arm 40 is moved toward a vertical position, thereby depressing pin 46' and openingjaws 31 and 36, releasing the grip on the thread 55 and allowing it to move freely, until the tension is sufficient to pull. the rider 2311p against the action of spring 24. hen the rider 23 has been raised sufficiently it moves the projection3 upward, out of the path of the teeth 54, and thus releases the nearest tooth 54,

. tighten their grip on the thread, and thereby hold it taut. The tension being released on the thread between eyes 28 and 25 the rider 23' is forced down by spring 24, thereby tightening the thread between the jaws 31 and 36 and eye 18, and causing the bobbin to revolve.

If the tension is released sufliciently to allow rider 23 to drop to the bottom of shaft 19, projection 3 will engage one of the teeth 54, thereby stopping the rotation of the bobbin B within a short distance.

It will be seen, therefore, that bobbin B will not feed more thread until the tension on thread 55 is sufficient to cause arm 40 to release jaws 31 and 36, and raise rider'23 out of engagement with one of the teeth 54.

It is apparent therefore that this device will provide thread, yarn or wire to the machine at a constant tension.

A plan view of the rotating driver discs of a braiding machine'described in the above first mentioned application, is shown in Fig. 5. As the .operation of these discs is described in detail in this application, it will only be necessary to say that the plate 1 of the supply carrier is grasped by the rotating driver disc 60 and transferred to disc 61, thence to disc62 etc., until 67 is reached. Each of these discs rotate in the direction indicated by the arrow. It is apparent, therefore, that the carrier moves in a sinuous path, first being rotated in one direction and. then in another. Disc 67 reverses the direction and starts the carrier back over a similar sinuous route. While following these paths, the carrier picks up considerable centrifugal motion, which, if in the feed-off direction, will cause the bobbin B to rotate faster than is necessary to provide taut yarn to the braider. This will cause a slack which will allow the let-off mechanism to operate as described above, and rider 23 will fall and engage one of the teeth 54 on disc 2 thereby stopping the rotation of bobbin B. This stop, which is necessarily abrupt, creates a danger of snapping the thread 55. This danger is overcome by means of spring 13 which is in cooperation with hollow shaft 10 as described above. The disc 20 which carries rod 19 and rider 23 is attached toshaft 10 which is capable of rotating until the limit of spring 13 is reached. It is clear that the mechanism of bobbin B will cause the plate 20 to rotate through the medium of rider v23. When the limit of spring 13 is reached and the centrifugalforce dissipated, the plate 20 wi'llbe rotated in a reverse direction, the retarded oscillation caused thereby taking up 2. In a thread carrier for sinuous path.

braiding machines, a carrier base, a thread support mounted rotatably thereon, means to regulate rotation of said support relativelyto said base, for delivery of thread and a spring to oppose yieldingly the oscillation of said thread support caused by rotative movement of said base in either direction relativelyto said thread support during its of said thread support.

3. In a thread carrier for sinuous path braiding machines, a carrier base, a thread support mounted rotatably thereon, means to regulate rotation of said support relatively to said base, for delivery of thread and means to oppose yieldingly the oscillation of said thread support caused by rotative movement of said base in either direction relatively to said thread support during its progress througha sinuous path and thereby to control corresponding rotative movements of said thread support.

4. In a thread carrier for sinuous path braiding machines, a carrier base, a thread support mounted rotatably thereon, a let-off mechanism comprising frictional means adapted to act directly upon thethread from said supper to retard withdrawal thereof, a tension device to take up slack in the thread delivered from said retarding means, a connection between said tension device and retarding means to insure delivery of the supply under constant tension, means whereby the forward feeding rotation of said thread support relatively to said base is retarded variably as the draft upon the thread varies, and means to facilitate oscillating rotative movement of said base relatively to said thread support during its progress through a sinuous path without corresponding rotative movements of said thread support.

5. In a thread carrier for sinuous path braiding machines, a carrier base, a thread support mounted rotatably thereon, a let-off mechanism comprising in part a pawl member adapted to be raised and lowered as the draft on the thread from said support varies; a circular plate secured to said thread support with teeth thereon for co-operation with said pawl member, said pawl and teeth holding said thread support from rotating wlth relation to said let-ofi' when the draft on said thread is lessened, and means to oppose yieldingly the oscillationof said thread support caused by'rotative movement of said base relatively to said plate during its progress through a sinuous path and thereby to control corresponding rotative movements of said plate, and tending constantly to restore saidplate to a predetermined normal position relatively to said base.

6. In a thread carrier for sinuous path braiding machines, a carrier base, a thread support mounted rotatably thereon, a let-ofi mechanism mounted on said base comprising 1n part a pawl member adapted to be raised and lowered as the draft on the thread from sald support varies; a circular plate secured to said thread support with teeth thereon for co-operation with said pawl member, said pawl and teeth holding said thread support from rotating with relation to said let-off when the draft on said thread is lessened, and means to oppose yieldingly the oscillation of said thread support caused by rotative movement of said base relatively to said thread support during its progress through a sinuous path and thereby to control corresponding rotative movements of said thread support. r

7, In a thread carrier for sinuous path bra1d1ng machine, a carrier base, a let-off mechanism comprising in part a post mount ed'on a circular plate which is mounted on a hollow shaft, said shaft being free to rotate on said base, a second hollow shaft carrymg a thread support positioned there between and fastened to said base and first shaft, a circular plate having teeth thereon secured to said second shaft, said post having a pawl member mounted slidably thereon adapted to be raised and lowered as the draft on the thread from-said support varies, saidspecification. i

HARRY G. ROBINSON. 

